This research proposal is concerned with the representations and processes underlying spoken word recognition. The long-term objective of the proposed research is to understand more fully how the human listener so rapidly and efficiently isolates a unique word from among the tens of thousands of words stored in memory. In particular, this research is aimed at understanding the processes involved in the activation of acoustic- phonetic patterns in memory and the processes responsible for deciding among these patterns. This research is based upon and motivated by a recent model of spoken word recognition called the neighborhood activation model. The specific aims of this proposal focus on extending and elaborating the neighborhood activation model in two ways. First, this research will attempt to determine the degree to which the spoken word recognition system operates according to the principle of least commitment, deferring decisions on ambiguous information until later, disambiguating information is processed. Second, this research will attempt to determine the nature of the temporal window in which information in the acoustic-phonetic waveform is mapped onto lexical items in memory. To accomplish these goals, a number of different experimental paradigms and stimuli will be employed. The experimental paradigms include speeded paired comparison tasks, acoustic-phonetic and semantic priming tasks, auditory lexical task. Specially constructed word and nonword stimuli will be generated to test the specific issues cited above. The overall goal of this research is to investigate in detail the means by which the spoken word recognition system appears to operate so quickly yet with such a high degree of accuracy.